Natural products are substances produced by microbes, plants, and other organisms. Microbial natural products offer an abundant source of chemical diversity, and there is a long history of utilizing natural products for pharmaceutical purposes. One such compound is FR901228 isolated from Chromobacterium and has been found to be useful as an antibacterial agent and antitumor agent (see, for example, Ueda et al., U.S. Pat. No. 7,396,665).
However, secondary metabolites produced by microbes have also been successfully found to have uses for weed and pest control in agricultural applications (see, for example, Nakajima et al. 1991; Duke et al., 2000; Lydon & Duke, 1999; Gerwick et al., U.S. Pat. No. 7,393,812). Microbial natural products have been also successfully developed into agricultural insecticides (see, for example, Salama et al. 1981; Thompson et al., 2000; Krieg et al. 1983). Sometimes, such natural products have been combined with chemical pesticides (see, for example, Gottlieb, U.S. Pat. No. 4,808,207).
Burkholderia 
The Burkholderia genus, β-subdivision of the proteobacteria, comprises more than 40 species that inhabit diverse ecological niches (Compant et al., 2008). The bacterial species in the genus Burkholderia are ubiquitous organisms in soil and rhizosphere (Coenye and Vandamme, 2003; Parke and Gurian-Sherman, 2001). Traditionally, they have been known as plant pathogens, B. cepacia being the first one discovered and identified as the pathogen causing disease in onions (Burkholder, 1950). Several Burkholderia species have developed beneficial interactions with their plant hosts (see, for example, Cabballero-Mellado et al., 2004, Chen et al., 2007). Some Burkholderia species have also been found to be opportunistic human pathogens (see, for example, Cheng and Currie, 2005 and Nierman et al., 2004). Additionally, some Burkholderia species have been found to have potential as biocontrol products (see for example, Burkhead et al., 1994; Knudsen et al., 1987; Jansiewicz et al., 1988; Gouge et al., US Patent Application No. 2003/0082147; Parke et al., U.S. Pat. No. 6,077,505; Casida et al., U.S. Pat. No. 6,689,357; Jeddeloh et al., WO2001055398; Zhang et al., U.S. Pat. No. 7,141,407). Some species of in this genus have been effective in bioremediation to decontaminate polluted soil or groundwater (see, for example, Leahy et al. 1996). Further, some Burkholderia species have been found to secrete a variety of extracellular enzymes with proteolytic, lipolytic and hemolytic activities, as well as toxins, antibiotics, and siderophores (see, for example, Ludovic et al., 2007; Nagamatsu, 2001).
Oxazoles, Thiazoles and Indoles
Oxazoles, thiazoles and indoles are widely distributed in plants, algae, sponges, and microorganisms. A large number of natural products contain one or more of the five-membered oxazole, thiazole and indole nucleus/moieties. These natural products exhibit a broad spectrum of biological activity of demonstrable therapeutic value. For example, bleomycin A (Tomohisa et al.), a widely prescribed anticancer drug, effects the oxidative degradation of DNA and uses a bithiazole moiety to bind its target DNA sequences (Vanderwall et al., 1997). Bacitracin (Ming et al., 2002), a thiazoline-containing peptide antibiotic, interdicts bacterial cell wall new biosynthesis by complexation with C55-bactoprenolpyrophosphate. Thiangazole (Kunze et al., 1993) contains a tandem array of one oxazole and three thiazolines and exhibits antiviral activity (Jansen et al., 1992). Yet other oxazole/thiazole-containing natural products such as thiostrepton (Anderson et al., 1970) and GE2270A (Selva et al., 1997) inhibit translation steps in bacterial protein synthesis. More than 1000 alkaloids with the indole skeleton have been reported from microorganisms. One-third of these compounds are peptides with masses beyond 500 Da where the indole is tryptophan derived. The structural variety of the remaining two-thirds is higher, and their biological activity seems to cover a broader range, including antimicrobial, antiviral, cytotoxic, insecticidal, antithrombotic, or enzyme inhibitory activity.